This invention is directed to the field of data processing control systems, particularly to integrated systems where a plurality of computers execute their logic in a coordinated manner within a network.
The primary application of the system described in this specification is for computerized control of machines deployed on a large physical scale (e.g. a chemical manufacturing facility), although benefits to endeavors related to plural computer processors, parallel computer processors, and networked computer processors are also enabled.
When computational demands or geographical constraints require the physical distribution of computing facilities (e.g. such as for process control in a large, geographically dispersed chemical plant), implementation factors (such as product quality) may benefit from centralized coordination of the computing tasks. This invention describes a system and method for enabling a plurality of geographically dispersed computers to be networked for enabling time coordinated inter-activity. This resultant network enables task coordination and facilitates the implementation of other qualities beneficial to the task being performed by the systemxe2x80x94qualities such as redundancy, security, and high throughput.
One embodiment of a system showing such substantive real-time networking to a set of physically distributed remote field units for use in a process control system is described the U.S. Pat. No. 5,428,769 issued on Jun. 27, 1995 and entitled xe2x80x9cProcess control interface system having triply redundant remote field unitsxe2x80x9d to Glaser, Robert S.; Hoy, Robert S.; Fernandez, G. Paul; and Grai, Timothy J. While the system is adequate for many process control situations, the networking methodology effectively addresses each system in each time period on the presumption that there is a need to do so; however, many of these addressing cycles are unnecessary if all variables for exchange are stablexe2x80x94a more elegant scenario from the standpoint of network efficiency would provide for communications only when the status of either the inputs or the outputs require change.
Physical distribution of computing facilities combined with centralized coordination of the computing tasks is also a driving concept in high performance processors characterized by parallelism. Vector processors, as discussed in sections 7.1 and 7.2 (xe2x80x9cVector Processorsxe2x80x9d) of Computer Architecture A Quantitative Approach by John L. Hennessy and David A Patterson (Morgan Kaufmann; San Mateo, Calif.; 1990; pages 351-363) are one manifestation of such systems, and processor-memory pair approaches such as the Cm★ design discussed from pages 11 to 18 of xe2x80x9cParallel Processingxe2x80x94The Cm★ Experiencexe2x80x9d by E. F. Gehringer, D. P. Siewiorek, and Z. Segall (Digital Press via Editorial Inc.; Rockport, Mass.; 1987) provide a second example of these types of approaches.
Centralized coordination of computing tasks in a scheduled context for the future also draws on concepts from traditional project scheduling such as is discussed from pages 569 to 584 of the text Productions and Operations Management by J. William Gavett (Harcort, Brace, and World; New York; 1968).
Process control systems development is characterized by an ever-increasing incorporation and management of issues at large in the system being controlled, requiring that a comparably larger amount of logic on a comparably larger amount of data be executed in a time frame which is not permitted to expand. This can be achieved to some degree by hardware which processes logic more quickly and holds more data in an addressed physical store, but there are substantial costs in pursuing this solution. What is needed to resolve the ability of future systems to effectively expand their comprehensive treatment of the control situation is to truly provide a solution path for enabling a very large number of distributed computers to execute massive amounts of logic in a mutual manner which is time-synchronous across an entire network. The present invention provides such a method and system.
To achieve the above objects, the present invention provides a computer implemented method for enabling a plurality of computer nodes in mutual data communication to execute logic in a coordinated manner by
aligning real-time time between the plurality of computer nodes so that each computer node has essentially the same real-time time;
defining a schedule of communications for each computer node, with the schedule having a different time in the future defined for initiating each respective communication;
communicating each schedule to its respective computer node; and
initiating each communication from each node at the time defined in its schedule.
Additional features and advantages of the present invention will become more fully apparent from a reading of the detailed description of the preferred embodiment and the accompanying drawings.